This invention relates to welding in general, and specifically for welding posts of batteries, as for example of the type used in automobiles.
In the welding of various members together, it is commonplace to use a welding rod having a flux therein, for many types of welding, such as arc welding. In other instances, particularly when the materials being welded together are soft, such as those comprising pot metal, lead, lead alloys or like materials, welding may be effected by application of open flame to members that are to be welded together. In many instances such techniques are highly desired and quite meritorious.
However, in some instances, as for example when electrical conductivity is desired, it becomes paramount that the connection between members being welded be such as to create minimal electrical resistance.
In the art of battery manufacture, particularly wet cell batteries for automobile usage and the like, it has become commonplace to utilize wet cell batteries, having a plurality of cells. In each cell, there are disposed a plurality of parallel but spaced plates, each having a lug extending therefrom, with the various lugs being interconnected by a battery strap, by any suitable means, such as that disclosed in U.S. Pat. No. 3,395,748. Extending from a strap of this type which connects plates of a given cell, is a post. Adjacent cells of a given battery are separated by cell partitions. Posts of groups of plates in adjacent cells must be connected, for electrical conductivity between cells. Accordingly, it is this connection of adjacent battery cell posts that is of primary concern in this application.
Because of the presence of a cell partition between the posts, the posts are somewhat spaced at their upper ends, in that the posts extend generally upwardly above the height of the cell partitions, such upward extension or protrusion facilitating the application of heat thereto, for obtaining an electrical connection between the posts across the upper end of an associated plate. Because of the necessity of obtaining good electrical conductivity across such post connections, the art of welding battery posts has become highly developed, with individuals for performing the same having developed a high degree of skill with respect thereto.
However, because such posts are generally spaced by the thickness of a cell partition, the flame achieved by the use of a gas-oxygen torch or the like must be raised to such a temperature that will permit the delivery of a sufficiently high temperature at the lower end of the spacing between adjacent posts, if it is desired to adhere the posts together as close as possible to the cell partition at the lower end of the spacing. However, in raising the welding temperature to such a level, excessive temperatures are reached at the uppermost ends of the posts, most closely located relative to the torch which accomplishes such "burning", such that early metal flow from the upper ends of the posts commences, such flow continuing down into the space between the posts, above the separator plate, and solidifying there, before lower ends of the posts in the vicinity of the upper end of the separator plate have become sufficiently heated, thereby resulting in an incomplete fusion of metal at a location corresponding to the upper edge of the cell partition. Thus, the result is that while a good fusion may exist at the upper ends of posts thus welded, often, at the lowermost ends of such posts, directly above the separator plate, the fusion is imperfect, with insufficient bond to provide sufficiently low electrical resistance as a connector. In order to avoid this, an operator may play the torch between the posts, in order to assure a good weld in the lower zone of such space above the separator plates or partitions, but such may cause the cell partitions to be scorched or damaged. Accordingly, the result is that present techniques of welding battery posts often results in variations or lack of uniformity in weldments of batteries, depending upon the particular operator or welder involved, as well as resulting in an undesirable percentage of rejects due to welds that have a sufficiently good external appearance to pass customary quality control, but which are really poor weldments. Furthermore, batteries having poor weldments of battery posts are more prone to cause operating difficulties.